1. Field of the Invention
The invention generally relates to a ramp voltage generator in a pulse width modulation system, and more particularly, relates to a ramp voltage generator that uses an integrator circuit with a reversing switch array.
2. Description of the Related Art
A periodic ramp voltage waveform is typically used to establish time intervals in pulse width modulation (PWM) systems. An integrator circuit comprising a current source and a capacitor is generally used to generate the periodic ramp voltage waveform. For example, the current source charges the capacitor at a constant rate to establish a voltage that increases with time (or ramp voltage) and the capacitor is periodically discharged to its starting voltage. The periodic discharge (or reset) of the capacitor between voltage ramps disadvantageously takes time (e.g., typically 5% of the waveform period) and the associated high discharge current may disturb power supply voltage levels (e.g., through power supply sag or ground bounce).